Communication between two switches with different subnets (M4100) M4100

Hi Rachakondaashok

The two subnets you describe (192.168.1.0 /24 and 192.168.0.0 /23) are in the same subnet range.

You want to connect two network segments, but how do you avoid duplicate IPs in this case? Building A PC device could get and IP of 192.168.1.24, but so could a device in building B. That is a problem!

Additionally, are you using VLANs or is everything in default VLAN1? If you are using just one VLAN, then you need to be careful because if you connect the switches together you will now have two DHCP servers for the same VLAN. That is never a good thing! But that could be solved with some quick DHCP snooping setup, however that still does not address the actual issue of duplicate IPs being a very likely problem.

Due to the fact that you need two DHCP servers, because you need two different Gateways for clients, then you need to separate those networks. What you could do is:
1. Create separate VLAN for people in building A, say VLAN10

2. Create separate VLAN for people in building B, say VLAN20

3. Use actual different subnets for those VLANs, say 192.168.0.0 /23 and 192.168.2.0 /23.

4. Create a second routing VLAN and use that between the switches, say VLAN99.

5. Setup some static routes on each router, to guide clients when they want to communicate with the other building.

This way you can create a routing path between devices in building A and building B, while still maintaining two different networks.

Cheers